1. Field of the Invention
The present invention relates to an image transmission apparatus and control method therefore, and an image display system.
2. Description of the Related Art
In recent years, there have been more opportunities to use a projector that projects onto a screen an image based on an image signal received from a PC during a presentation at a conference, a workshop, and the like.
In general, the PC and the projector transmit and receive the image signal through an image cable. However, there are problems, such as the connection is troublesome, the connection from a remote place is difficult, and there is a limitation in the number of PCs that can be connected at the same time. Therefore, an image transfer system that connects the PC and the projector through a network has been drawing attention in recent years.
Conventionally, an image processing apparatus such as a PC captures a specific window or an image of the whole screen, and image data obtained by the capture is transmitted to a display apparatus such as a projector to realize the image transfer system.
Conventionally, if the number of display pixels of the PC and the number of display pixels of the display apparatus, such as the projector, are different in the image transfer system, an image resolution converter is arranged on the display apparatus to convert the resolution of the image. If the number of display pixels of the PC is greater than that of the display apparatus, there is a problem that the image data is transmitted to the display apparatus without change, and an unnecessary load is imposed on the network.
To solve the problems, Japanese Patent Laid-Open No. 2006-106158 discloses, for example, a method in which the resolution of image data is converted in advance within the PC so that the number of display pixels of the PC matches that of the display apparatus, and then the image data is transmitted.
However, in the configuration described in Japanese Patent Laid-Open No. 2006-106158, when the resolutions between the PC and the display apparatus differ, there is a problem that it is necessary to perform the resolution conversion processing within the PC and the PC should take a considerable load of the resolution conversion processing. Furthermore, there is a problem that the image is deteriorated by reduction processing of the image because the image needs to be reduced when the number of display pixels of the PC is greater than the number of display pixels of the display apparatus.